1. Field
The instant invention relates to hybrid water bed mattress structures which have a thickness, width and length comparable to conventional innerspring single, double, queen and king size mattresses. Hybrid water bed mattresses are generally supported upon a rigid box-like structure in lieu of a box-spring support and have a weight substantially less than a conventional water bed.
2. Prior Art
In recent years, the bedding industry has developed a hybrid mattress which is a cross between a conventional water bed and a conventional innerspring or foam mattress. These hybrid or composite mattresses have a thin depth, for example, four to eight inches in depth, a water filled bladder and some means of restraining the bladder laterally. Generally, a foam cushion overlay rests upon the bladder to insulate the sleeper's body from the water bladder and to reduce some of the vibrations and waves caused by any motion upon the water-filled bladder.
Typical composite water bed mattresses which have been developed in recent years include the structures disclosed in U.S. Pat. Nos. 4,186,455, Fox et al.; 4,015,299, Tinnel; 3,840,921, LaBainco; 3,702,484, Tobinick; 4,062,077 and 4,145,781, Autrey et al.; 3,742,531, Alsbury; and 3,689,945, Weinstein.
The following patents, although directed to a more conventional water bed structure, disclose structures which are germane to composite water bed mattress structures. Examples of such patents include U.S. Pat. Nos. 3,736,604, Carson; 3,585,356, Hall, and 3,735,432, Kretin.
Other patents disclosing structures relating generally to water beds or structures which may be adapted in certain aspects to composite water beds include the following: U.S Pat. Nos. 3,778,852 (Penn); 3,787,908 (Beck); 3,864,768 (Fraige); 4,042,986 (Goodman); 3,581,322 (Marsico); 2,481,833 (Foster); 3,849,814 (Ross); 3,958,286 (Rodinsky); 3,308,491 (Spence); 1,371,362 (Giese); 3,728,747 (Docker); and 3,864,767 (Adams).
Each of the above-described patents has certain advantages and disadvantages. For example, in Autrey et al, U.S. Pat. No. 4,062,077, the vertical rigid restraining member is adjacent the bladder and must be substantially the same height as the bladder to avoid pinching the bladder against the upper surface of the rigid restraining member. Thus, if the bladder has a substantial thickness, for example four to six inches, the rigid restraining member height must be about the same height, allowing very little foam cushioning above the restraining member's thin edge inasmuch as conventional composite mattresses have a thickness from about six to eight inches. Thus, the restraining member is readily detected and is uncomfortable to sit upon or to lie upon when a bladder of about four inches or more in thickness is used. If thinner bladders are utilized in the Autrey et al. structure, then the flotation effect of the water-filled mattress is substantially diminished.
In the later patent of Autrey et al., a variation of the '077 structure fixes the rigid restraining member to a base.
In the Tinnel structure the restraining wall is a unitary foam construction. It is a flexible foam so it is comfortable to sit on, however, once the bladder is filled there is a tendency of the sidewalls of the structure to bow outwardly because of the hydrostatic pressures involved. Also, since the foam depresses significantly whenever anyone sits upon an edge, the safety reservoir feature is diminished inasmuch as the upper level of the liner is then moved to a position lower than the bladder height. In such an event, water spills out if the bladder has a major leak and water has filled the reservoir.
In Kretin et al. the rigid retaining members have a substantial vertical dimension which brings a thin edge to a position relatively close to the upper foam surface.
In U.S. Pat. No. 4,186,455 of Fox et al. several types of hybrid mattresses are disclosed and claimed. Many of these structures include a horizontal wooden slat in the sidewall of the mattress to provide lateral support. While sidewall structures incorporating a board perform satisfactorily, wooden slats or boards are occasionally characterized by non-uniformity of strength and quality, especially in the inexpensive wooden slats often used in hybrid mattresses. Thus, hybrid mattress sidewall structures which do not employ wooden slats but which resist outward bowing while comfortable to sit upon are desirable.
A hybrid structure without a board is also disclosed in U.S. Pat. No. 4,186,455 of Fox et al. Such multi-layer structures are characterized by a sidewall width which is greater than its height.
LaBianco (U.S. Pat. No. 4,057,862) discloses a peripheral retaining border composed of two wedge-shaped, foam members whose bases are much wider than their heights. A prior patent of LaBianco, U.S. Pat. No. 3,840,921, illustrates a single wedge-shaped peripheral retaining member for a water bed. The LaBianco structures are generally more closely related to conventional water bed structures than to hybrid water bed mattresses of the Tinnel type.
In U.S. Pat. No. 4,506,397 to Fogel et al., a soft-sided water bed is disclosed in which an upper framework has a foam periphery having a notched sidewall to interact with a lower peripheral frame-like member attached to a rigid base. An elongated substantially rigid, angular member is attached to the upper member such that the angular member, similar in structure to angle-iron, fits within the notch and is glued to the upper member to reinforce it.
Other water bed structures having internally slanted foam peripheral members are disclosed in U.S. Pat. Nos. 4,187,566 to Peterson, 4,197,602 to Johanning and 4,187,565 to Zeltzer.